The present invention relates to infant-support apparatus or incubators which have air circulation systems provided with air warmers, and, more particularly, to the provision of such a system with a fail safe device for the air warmer.
It is well known in the infant care industry to provide incubators with air circulation systems for controlling the environment within which an infant resides. Such an infant-support apparatus is shown, for example, in U.S. Pat. No. 6,024,694 to Goldberg, et al., the disclosure of which is herein expressly incorporated by reference. Typically, the environment is established by a canopy structure placed over a platform upon which the infant rests. Air is drawn into the environment by the air system and, typically, it is heated and moistened to provide a desired and controlled environment. To reduce the CO2 level in the environment, a certain amount of the air is removed from the enclosure and air is drawn in from the room in which the infant resides. The control of the temperature of the air is very important and, in some cases, critical to the well being of the infant. Typically, the air is heated to the desired level by a heat exchanger of the type shown, for example, in the U.S. Pat. No. 5,707,006 to Skulic, (xe2x80x9cthe Skulic ""006 patentxe2x80x9d) issued Jan. 13, 1998, the subject matter of which is incorporated herein by reference. The Skulic ""006 patent shows a heat radiator for heating the air circulating through an incubator. The radiator has a plurality of radially extending fins carried or mounted on a heater cartridge. The heater of the present invention, however, provides an improvement over the heater disclosed in the Skulic ""006 patent. The improvement is a fail safe device for such a heater.
In accordance with the present invention, the air warmer or air heater comprises a heater element, a plurality of air-contacting fins associated with the heater element, and a sensing element in contact with at least a portion of the fins. The sensing element is separate from the heater element. In embodiments of the present invention, the heater element is an elongated element or heating cartridge with a proximal end and a distal end. The plurality of fins are spaced apart along the heater element. The sensing element extends longitudinally alongside and separated from the heater element to contact the fins.
In an illustrative embodiment, a primary temperature sensor is associated with the heater element, and is located at the distal end of the heater element. Then, the fail safe device comprises a separate sensing element in contact with at least a portion of the fins, and a control system for the assembly responsive to the primary sensor and the separate sensing element. In such an embodiment, the separate sensing element is a metal rod, such as an aluminum rod, spaced apart from the heating element and extending through aligned openings disposed through the fins. The sensing element is in heat transfer contact with the fins such that convective heat transfer between the sensing element and fins is facilitated so that the sensing element generates a signal indicative of the temperature of the fins when the fins are present. This elongated metal rod has a proximal end and a distal end, and a heat sensor is located at a proximal end of the metal rod to establish the temperature of the fins in contact with the rod. It will be appreciated that this second sensing element will detect if a service person has cleaned but failed to reinstall the fin assembly on the heater element as radiant heat absorbed by the sensing element from the heater element will not be dissapated through transfer to the missing fin assembly.
An illustrative embodiment comprises a separate heat sensor in contact with at least a portion of the fins of an air warmer to provide a separate indication of the temperature to which the fins are heated. The output of this second sensor is usable to control the heater system of the incubator. If the temperature of the sensing element is excessive or in some manner not within specified predetermined limits, the control system may provide alarm signals to the caregivers, and if the heat is excessive, shut down the heating system to avoid injury to the infant.
The control system for the heater system may shut down the power to the heater element in the event the separate heat sensor reads a temperature in excess of a preset limit or in the event the difference between the temperature read by the primary sensor and the separate sensor is too great.
In illustrative embodiments, the heater element and the separate heat sensor comprise upstanding, post-like structures which are configured to be received in a central bore of a longitudinally extending hub of the fin assembly from which the fins radiate and in a laterally spaced bore through a portion of the hub and the fins. The fin assembly is lowered vertically downwardly on the upstanding heater element and heat sensor to be held in place by gravity. For heat transfer, the heater element and sensor are in sliding contact with the fin assembly.
Additional features and advantages of the device will become apparent to those skilled in the art upon consideration of the following detailed descriptions exemplifying the best mode of carrying out the device as presently perceived.